Hypselodoris bullockii is a species of colorful sea slug or dorid nudibranch, a marine gastropod mollusk in the family Chromodorididae. Hypselodoris bullockii is quite variable in color. What may be another species has been named Hyselodoris apolegma; it looks quite similar to this species and may turn out to be merely a different color form of H. bullockii. Originally described from the South China Sea, this species is found in the western Pacific as far south as southern Queensland. It is also found in north western Australia and Thailand. It ranges in colour from a pale straw, or even white background to a deep purplish pink. There is usually a thin opaque white line at the mantle border, but some specimens have a reddish purple border. Typically the gills and rhinophores are yellow or orange with a basal pink or purplish band